1. Field of Invention
The invention relates generally to a wall plate adapter that replaces existing wall plates of electrical outlets and, more particularly, to a wall plate adapter that includes circuitry for interacting with a home network via the AC power wiring of the electrical outlets.
2. Description of Related Art
Various types of home automation networks are currently available for controlling different functions in the home, such as heating and cooling, lights, home entertainment, kitchen appliances, computers, sprinklers and security devices. In particular, networks such as those conforming to the X10 standard use the existing alternating current (AC) power lines in a home or other structure as a network media to carry data. Such networks can include transmitter units, receiver units, and bidirectional units that can receive and transmit commands. X-10 transmissions are synchronized to the zero-crossing point of the AC power line. A binary 1 is represented by a 1 ms burst of 120 KHz at the zero-cross point and a binary 0 by the absence of a burst. The receiving units may perform various functions such as turning the power on or off to an appliance such as a lamp, or adjusting the amount of power provided to the appliance, such as to provide a dimming function for a lamp. Transmitter units may send predefined commands to a specified receiving unit automatically, such as based on a timer, or based on a manual user command, such as the activation of a switch on a control panel. Bidirectional units may send their current status (e.g., on or off) upon request. Furthermore, an address can be associated with each device so that individual devices can be controlled.
Typically, control signals are coupled to the power lines in a home or other structure using either standalone adapters or low-voltage transformers with the coupling circuitry built in. However, when a separate adapter is used, a typical system uses two AC receptacles, causing inconvenience to the end user. Moreover, if the coupling circuitry is built into the low-voltage transformer, multiple versions of the transformer are needed for use with different output voltages. This results in additional design time and cost.